ADWR History

In Arizona, as in all arid regions, water means life. Arizona faces more severe constraints on its water supply than almost any other state in the nation.

When we compare our State’s average annual precipitation of 12.32 inches to the 30.21-inch average experienced by other US states, it is not surprising that the name "Arizona" comes from the Native American word "arizonac," meaning "the place of the small spring."

Astute settlers in the 1860s re-established some of the gravity-powered irrigation canals from the previous generation of Native American tribes to bring water to crops in the large valleys of central Arizona. The settlers constructed new networks along those lines with a similar layout that moves water to this day.

In the late 19th Century, Arizonans experienced storms that transformed normally calm streams into frightening floodwaters. They came to understand more about the patterns of water flowing during different seasons in and away from their communities.

This awareness and their ability to harness the power of water led the way to successful irrigation and canal projects. In 1911, the U.S. Bureau of Reclamation completed its first major project in the region, Roosevelt Dam. One of the world's highest masonry dams, this project gave Arizonans the ability to control floods, irrigate, and generate hydroelectric power in many communities.

Areas outside the reach of irrigation canals still needed to rely on groundwater. Parts of Arizona had ample supplies of it, but as demand for irrigated croplands grew, the aquifer depletion occurred. Since the early 1930s, State officials recognized that action was required to control overdraft of Arizona's groundwater basins.

Today, this history continues to impact the agency's mission. Please explore and learn more about the Arizona Department of Water Resources!

Beginning in the 1930s, groundwater pumping in central Arizona increased as a result of higher cotton prices, new pump technologies, and lower energy costs. In certain areas, the increased groundwater pumping resulted in wells going dry and land subsidence, or a gradual sinking of the Earth's surface, occurring. In response to concerns about unregulated groundwater pumping, the Arizona Legislature enacted laws in 1948 prohibiting the drilling of new wells to irrigate lands within ten "critical groundwater areas."

Despite the enactment of the 1948 groundwater laws, groundwater pumping continued to increase in many areas of the State, causing additional groundwater declines and subsidence. Bills were introduced in the Legislature in 1952 and 1953 to impose additional restrictions on groundwater pumping, but those measures failed.

The tipping point came in 1976 with the Arizona Supreme Court’s decision in Farmers Investment Company vs. Bettwy. The high court ruled that a private company of pecan growers could impose a limit on how much groundwater a municipality - in this case, Tucson - and the nearby copper mines could pump. Following this decision, Arizona cities and the mining industry demanded State legislative action.

In response, the Legislature formed a 25-member groundwater management study commission to propose new groundwater laws.

The three primary issues were:

Who should have the right to pump groundwater and how much?

What methods should the State consider in reducing groundwater overdraft?

Should groundwater be managed primarily at the state or local level?

Continuing the path of unregulated groundwater pumping would threaten the state's expanding population and economy by depleting this vital resource and creating additional land subsidence. Farmers proposed that anyone looking to initiate new groundwater pumping should be required to purchase an existing right. An alternative proposal by the mining industry was that each groundwater basin receives a "quantified right" to groundwater. The disagreements among the groups continued.

The cities and mines brought things to a head when they garnered enough support to potentially pass several provisions that were opposed by agriculture representatives. A path to an agreement looked unlikely.

In 1979, Governor Bruce Babbitt and State legislators were at an impasse over how to proceed. Babbitt convinced the U.S. Secretary of the Interior, Cecil Andrus, to issue an ultimatum: unless Arizona enacted tough groundwater laws, he would refuse to approve construction of the Central Arizona Project (CAP). Because the allocations were due in 1980 to keep funding of the CAP on track, this ultimatum threatened to delay, and possibly kill the CAP.

After some initial shock, the cities, mines, and agriculture asked Babbitt to mediate the discussions of the study commission. One of the first items agreed to by the study commission was to create the Arizona Department of Water Resources as the State agency empowered to administer and enforce groundwater laws in the State.

On June 12, 1980, Governor Babbitt signed the Groundwater Management Act. For the first time, one state agency was responsible for all water planning and regulation in the State, except for water quality. That duty would be assigned to the Arizona Department of Environmental Quality. The law designated four areas of the State where groundwater pumping was heaviest as "Active Management Areas," or AMAs.

The Groundwater Management Act generally does not regulate groundwater use in areas outside of AMAs but instead requires only that groundwater be put to reasonable and beneficial use. However, the Act designated two areas (now three) outside of AMAs as irrigation non-expansion areas, where the irrigation of new lands is prohibited. In all areas of the State, the Act requires wells to be registered with ADWR and new wells to be constructed in compliance with ADWR’s well construction standards. The Act also imposes restrictions on transporting groundwater away from groundwater basins.

To address groundwater overdraft in the AMAs, the Act established a management goal for each AMA, which for the Phoenix, Prescott and Tucson AMAs is to attempt to achieve safe-yield by 2025. To assist each AMA in achieving its management goal, the Act requires ADWR to adopt a series of five management plans for each AMA that include mandatory conservation requirements for persons withdrawing, using or distributing groundwater. The Act also requires developers of new subdivisions within AMAs to demonstrate that their subdivisions will have a 100-year assured water supply and that any groundwater use will be consistent with the AMA’s management goal as determined by rules adopted by ADWR.

The Groundwater Management Act was the most anticipated and far-reaching water policy initiative ever undertaken by the State of Arizona. This progressive law created new responsibilities and authority that led to recognition in 1986 by the Ford Foundation for its landmark work in water management.

ADWR Timeline

The Howell Code established the doctrine of prior appropriation for surface water in Arizona. This doctrine provides that the person who first puts the water to a beneficial use acquires a right that is senior to later appropriators of the water.

1902 - President Theodore Roosevelt signs the National Reclamation Act

The Reclamation Act recognized that a key component to growth in the West is to have a system that manages irrigation, storage, diversion and the development of water resources. This Act paved the way for important projects in the West such as funding for the construction of the Roosevelt Dam and resulted in the creation of the U.S. Bureau of Reclamation.

1903 - The Creation of the Salt River Project

The Salt River Valley Water Users’ Association was formed to facilitate construction of and repayment for the Salt River Project, the nation’s first multipurpose water and power reclamation project commenced under the National Reclamation Act.

1911 - The Construction of the Roosevelt Dam is Completed

President Theodore Roosevelt dedicated the Roosevelt Dam, the tallest masonry dam at the time. Construction of the dam contributed significantly to the settlement of central Arizona.

1919 - The Arizona Legislature Adopts the Public Water Code

This law required a person to apply for and obtain a permit to appropriate surface water before putting that water to beneficial use. It replaced the previous method of merely putting the water to beneficial use or posting a notice at the point of diversion, recording a copy of the notice with the County Recorder and then putting the water to beneficial use.

1922 - The Establishment of the Colorado River Compact

The Compact among Arizona, Colorado, New Mexico, Utah, Wyoming, Nevada and California divided the Colorado River Basin into an Upper Basin and Lower Basin. This Compact appropriated 7.5 million acre-feet of Colorado River water per year to each basin. It also provides a right to the Lower Basin to increase its beneficial consumptive use of such waters by one million acre-feet (MAF) per year. Arizona refused until 1944 to ratify the Compact over concerns about the allocation of water among states.

1928 - Congress Passes the Boulder Canyon Project Act

The Act approved the construction of the Hoover Dam on the condition that the Colorado River Compact become effective. This Act provided a mechanism for making the Colorado River Compact effective without Arizona’s approval, and authorized the Lower Basin States to enter into a compact apportioning the Lower Basin’s 7.5 MAF among the States of California (4.4. MAF), Arizona (2.8 MAF), and Nevada (0.3 MAF). It also designated the Secretary of the Interior as the contracting authority for Colorado River water stored behind the Hoover Dam.

1935 - Completion of the Hoover Dam and the Creation of Lake Mead

Following its completion, the Hoover Dam began serving several important purposes on the Colorado River in the Lower Basin. These purposes include river regulation, improvement of navigation, flood control, hydroelectric power generation, and storage of water for beneficial uses within the Lower Basin States and Mexico. Hoover Dam, located in Nevada and Arizona, created Lake Mead, the largest human-made reservoir in the United States.

1944 - The Signing of the Mexican Water Treaty

The United States and Mexico signed a treaty that provided an annual allocation of Colorado River water to Mexico of 1.5 MAF.

1944 - Arizona Approves the Colorado River Compact

Governor Sidney Preston Osborn announced a policy shift on the Colorado River Compact. Arizona approved the Compact in hopes of getting approval for a reclamation project to deliver Colorado River water to central and southern Arizona (Central Arizona Project).

In response to warnings by the U.S. Bureau of Reclamation that the Central Arizona Project approval would not occur without restrictions on groundwater use, the Legislature required the registration of wells throughout the State (1945) and prohibited the drilling of new irrigation wells in ten designated Critical Groundwater Areas (1948).

1963 - The Supreme Court Upholds the Boulder Canyon Project of 1928

The United States Supreme Court ruled in favor of Arizona in a lawsuit filed by Arizona against California that disputed the claims to Colorado River waters in the Lower Basin. The decision determined Arizona’s Colorado River annual basic apportionment to be 2.8 million acre-feet, California's to be 4.4 million acre-feet and Nevada's to be 300,000 acre-feet. The decision allowed each state the exclusive use of its respective tributary water, a key reason Arizona did not initially ratify the Colorado River Compact. The decision also secured the water rights for Indian Reservations and other federal lands. Finally, the decision established the Secretary of the Interior as the Water Master of the Colorado River below Lee Ferry and granted the Secretary discretion, with some limitations, to determine how much water each state in the Lower Basin should receive during times of shortage.

1964 - Congress establishes the Land and Water Conservation Fund

President Lyndon B. Johnson signed an Act establishing the Land and Water Conservation Fund. The fund, championed by Arizona Congressmen Mo Udall, supports protection of federal land and water and provides incentives to states to develop public recreation areas and parks. Since its passage, the fund has resulted in over 2.3 million acres of protected land and the creation of over 40,000 state projects throughout the nation.

1966 - The Completion of Glen Canyon Dam and the Creation of Lake Powell

Following its completion, Glen Canyon Dam began serving several purposes on the Colorado River in the Upper Basin, including storing water for use by the Upper Basin States, especially during times of drought, and for making water deliveries to the Lower Basin States as required by the Colorado River Compact. Other purposes served by the dam include flood control, hydroelectric power generation, and recreation. Glen Canyon Dam created Lake Powell, the second largest reservoir in the nation behind only Lake Mead.

1968 - Congress passes the Colorado River Basin Project Act

Following persistent leadership by Arizona Congressmen John Rhodes and Mo Udall and Arizona Senator Carl Hayden, President Lyndon B. Johnson signed the Act authorizing the construction of the Central Arizona Project (CAP). Upon signing, the President proclaimed the day “Carl Hayden Day” at the White House to commemorate the passage. As part of the compromise needed to gain its passage, the Act includes a provision that specifies that diversions for the CAP are given a junior priority. This mean CAP water deliveries would be reduced before any reductions were made to California’s 4.4 MAF allocation when insufficient mainstream Colorado River water is available to satisfy 7.5 MAF of annual consumptive use in the Lower Basin.

The CAWCD is created to repay the federal government for the State’s share of the cost of the CAP and is authorized to operate the canal.

1980 - Arizona Legislature Passes the Groundwater Management Act

Governor Bruce Babbitt signed the Groundwater Management Act which was championed by State legislative leadership that included Stan Turley, Burton Barr, and Alfredo Gutierrez. The Act implemented the recommendations of the Groundwater Management Study Commission, which was composed of city, mine and agriculture stakeholders. Through its passage, the Arizona Department of Water Resources was established to administer the provisions of the Act, exercise jurisdiction over surface water, and represent the State on Colorado River issues. The Act also requires that developers of new subdivisions within Active Management Areas (AMAs) demonstrate a 100-year assured water supply.

The Arizona Legislature enacted legislation requiring CAWCD to replenish excess groundwater use by member service areas and member lands in Maricopa, Pinal and Pima counties to assist municipal water providers and new subdivisions in demonstrating an assured water supply. While performing its groundwater replenishment duties, CAWCD is commonly referred to as the Central Arizona Groundwater Replenishment District.

1995 - Adoption of the Assured and Adequate Water Supply rules

ADWR adopted rules establishing the criteria that developers and municipal water providers must meet to demonstrate a 100-year assured or adequate water supply.

1996 - Establishment of the Arizona Water BankING Authority (AWBA)

The AWBA stores Arizona's unused Colorado's River water underground in central and southern Arizona to protect certain cities, towns, and Tribes against future shortages in Colorado River supplies. The AWBA is also authorized to enter into interstate water banking agreements with Nevada and California.

2004 - Congress Passes the Arizona Water Settlements Act

President George W. Bush signed legislation led by Arizona U.S. Senator Jon Kyl, that approved an agreement between the U.S. and CAWCD for Arizona’s CAP’s repayment obligation. The Act also settled water rights claims of the Gila River Indian Community and the Tohono O'odham Nation and reallocated 67,300 acre-feet of unallocated CAP water to the Secretary of the Interior for use in future Indian water rights settlements in Arizona.

2007 - Arizona Legislature Enacts Mandatory Water Adequacy

Governor Janet Napolitano signed a bipartisan measure authorizing counties and cities outside of AMAs to adopt a requirement that new subdivisions demonstrate a 100-year adequate water supply, similar to the assured water supply requirement in the AMAs. Cochise and Yuma counties, as well as several cities, subsequently adopted the requirement.